Surprise
Paradox

Title:

Surprise Paradox

Author:

Joachim Breitner (joachim /at/ cis /dot/ upenn /dot/ edu)

Submission date:

2016-07-17

Abstract:

In 1964, Fitch showed that the paradox of the surprise hanging can be
resolved by showing that the judge’s verdict is inconsistent. His
formalization builds on Gödel’s coding of provability. In this
theory, we reproduce his proof in Isabelle, building on Paulson’s
formalisation of Gödel’s incompleteness theorems.